Not baby related, I need some advice though

My only brother (it's just him and I, no other siblings) is getting married in September and I was not asked to be in the wedding, but I was asked to be a personal attendant. I'm secretly really bummed out about it and feel a little left out seeing as he is my only brother. The bride and I aren't particularly close, but my brother is including the bride's sister's boyfriend in the wedding party because "he will be family some day". I know ultimately it's the brides choice, but my brother and I are close. I said yes, and I will make the most of it, I'm just a little hurt. Am I wrong for feeling left out and hurt?